President Trump arriving at Joint Base Andrews in Maryland after visiting Iraq. A British aviation enthusiast spotted the unannounced outward flight from his kitchen window.CreditCreditAl Drago for The New York Times

By Anna Schaverien

Dec. 28, 2018

LONDON — It’s hard to keep a secret when the internet is watching. Especially if plane spotters are involved.

Reporters accompanying President Trump on his visit to American troops in Iraq on Wednesday, his first to a combat zone, were sworn to silence. Air Force One was given a call sign that identified it as a military cargo flight. Mr. Trump himself later marveled at having traveled on a “darkened plane, with all windows closed, with no lights on whatsoever, anywhere — pitch black.”

But that wasn’t enough to stop a semiretired information technology specialist in Sheffield, England, from spotting and photographing the jet, or to prevent fellow aviation enthusiasts online from deducing what was happening, hours before Mr. Trump arrived at Al Asad Air Base in Iraq.

The information technology specialist, Alan Meloy, who describes himself on the photo-sharing website Flickr as “a lifelong aviation nut,” looked out from his kitchen window in Chapeltown, a suburban district of Sheffield, on Wednesday morning and saw an unusual plane flying above. He quickly took a long-lens photograph and posted it online.

“It was a lovely sunny morning,” Mr. Meloy told the BBC. “I looked up and as soon as I saw it I thought, ‘That’s shiny.’ It was in a clear blue sky and perfectly lit.”

Internet sleuths quickly deduced that the plane flying at around 31,000 feet was a Boeing VC-25, the military version of a 747 airliner. Only two aircrafts of that type are in service, and both are used for the American president’s transport.

Using publicly available tracking data, a community of plane spotters was able to determine that Mr. Trump was headed toward the Middle East long before any announcement about his visit was made.

“The internet had worked it out several hours before the White House formally confirmed the visit was taking place,” Mr. Meloy wrote about the photo he had posted on Flickr. He declined to be interviewed by The New York Times.

The discovery was a reminder of just how much flight data is publicly available today, and how much that could complicate established security routines.

“There are several apps that you can get on your smartphone or computer where you can track civilian planes from the point of departure right through to arrival,” said Norman Shanks, who once served as chief of security at Britain’s former largest airport operator.

He described the sighting of the president’s plane as “a lucky observation by an individual,” but added that the tracking of Air Force One’s flight path by aircraft enthusiasts was not likely to place the president in any danger.

“Did it put the aircraft at risk?” he said. “Probably not.”

Secrecy would not have been the only thing protecting Air Force One, said Bob Ayers, a security consultant who worked as an intelligence officer for 30 years.

“There is not any one security safeguarding for an Air Force One flight,” he said. “There is a whole family of protections in place that are operating at the same time.”

Mr. Trump, speaking before Mr. Meloy’s and other plane spotters’ detective work was widely known, certainly seemed impressed with the measures taken to keep his journey confidential. “I’ve never seen it,” he said on Wednesday of how Air Force One’s interior had been blacked out. “I’ve been in many airplanes — all types and shapes and sizes. I’ve never seen anything like it.”

A version of this article appears in print on , on Page A4 of the New York edition with the headline: How a British ‘Aviation Nut’ Cracked the Top-Secret Visit to Iraq by Trump. Order Reprints | Today’s Paper | Subscribe